DARTS: an open-source Python pipeline for Ca2+ microdomain analysis in live cell imaging data

Ca2+ microdomains play a key role in intracellular signaling processes. For instance, they mediate the activation of T cells and, thus, the initial adaptive immune system. They are, however, also of utmost importance for activation of other cells, and a detailed understanding of the dynamics of these spatially localized Ca2+ signals is crucial for a better understanding of the underlying signaling processes. A typical approach to analyze Ca2+ microdomain dynamics is live cell fluorescence microscopy imaging. Experiments usually involve imaging a larger number of cells of different groups (for instance, wild type and knockout cells), followed by a time consuming image and data analysis. With DARTS, we present a modular Python pipeline for efficient Ca2+ microdomain analysis in live cell imaging data. DARTS (Deconvolution, Analysis, Registration, Tracking, and Shape normalization) provides state-of-the-art image postprocessing options like deep learning-based cell detection and tracking, spatio-temporal image deconvolution, and bleaching correction. An integrated automated Ca2+ microdomain detection offers direct access to global statistics like the number of microdomains for cell groups, corresponding signal intensity levels, and the temporal evolution of the measures. With a focus on bead stimulation experiments, DARTS provides a so-called dartboard projection analysis and visualization approach. A dartboard projection covers spatio-temporal normalization of the bead contact areas and cell shape normalization onto a circular template that enables aggregation of the spatiotemporal information of the microdomain detection results for the individual cells of the cell groups of interest. The dartboard visualization allows intuitive interpretation of the spatio-temporal microdomain dynamics at the group level. The application of DARTS is illustrated by three use cases in the context of the formation of initial Ca2+ microdomains after cell stimulation. DARTS is provided as an open-source solution and will be continuously extended upon the feedback of the community. Code available at: 10.5281/zenodo.10459243.

Hyperactivity is a Core Endophenotype of Elevated Neuregulin-1 Signaling in Embryonic Glutamatergic Networks

The neuregulin 1 (NRG1) ErbB4 module is at the core of an "at risk" signaling pathway in schizophrenia. Several human studies suggest hyperstimulation of NRG1-ErbB4 signaling as a plausible pathomechanism; however, little is known about the significance of stage-, brain area-, or neural cell type-specific NRG1-ErbB4 hyperactivity for disease-relevant brain endophenotypes. To address these spatiotemporal aspects, we generated transgenic mice for Cre recombinase-mediated overexpression of cystein-rich domain (CRD) NRG1, the most prominent NRG1 isoform in the brain. A comparison of "brain-wide" vs cell type-specific CRD-NRG1 overexpressing mice revealed that pathogenic CRD-NRG1 signals for ventricular enlargement and neuroinflammation originate outside glutamatergic neurons and suggests a subcortical function of CRD-NRG1 in the control of body weight. Embryonic onset of CRD-NRG1 in glutamatergic cortical networks resulted in reduced inhibitory neurotransmission and locomotor hyperactivity. Our findings identify ventricular enlargement and locomotor hyperactivity, 2 main endophenotypes of schizophrenia, as specific consequences of spatiotemporally distinct expression profiles of hyperactivated CRD-NRG1 signaling.

[Imaging features of retained surgical foreign bodies]

PURPOSE

To study the clinical and radiological manifestations in patients with retained surgical foreign bodies.

PATIENTS AND METHODS

Over the last five years, seven patients were found to have retained surgical foreign bodies after abdominal surgery. An analysis of the clinical signs, laboratory findings and imaging features was performed.

RESULTS

The clinical and laboratory data were non-specific. The diagnosis of textiloma was suggested based on imaging findings and surgical history before surgical exploration. The characteristic imaging findings at ultrasound and computed tomography consisted of a fluid collection with internal wavy structures. The differential diagnosis includes pyogenic abscesses, hematomas and ruptured hydatid cysts.

CONCLUSION

Ultrasonography and computed tomography are essential for the diagnosis and management of retained surgical foreign bodies after abdominal surgery.

Determination of monoamine oxidase B activity by high-performance liquid chromatography with electrochemical detection

A sensitive high-performance liquid chromatography method with electrochemical detection for measuring monoamine oxidase B activity in blood platelets is described. Dopamine is used as substrate and is incubated with isolated platelets and aldehyde dehydrogenase to convert dihydroxyphenylacetaldehyde to dihydroxyphenylacetic acid (DOPAC). The acid and the added internal standard hydrocaffeic acid are separated from dopamine and the incubation mixture by extraction with 5 ml of ethyl acetate-toluene (5:1, v/v). The organic phase is evaporated under nitrogen stream and the residue dissolved in 0.1 M citric acid. Dihydroxyphenylacetic acid and the internal standard dihydrocaffeic acid are then separated on a Eurosphere 100-C18 5 microns column. The mobile phase used was a mixture of sodium acetate, citric acid, and acetonitrile at pH 2.5. The standard curve was linear from 125 pg to 10 ng. Absolute recovery of DOPAC was 85 +/- 3.8% and of hydrocaffeic acid 87 +/- 4.1%. The method presented is sensitive (detection limit 8.0 pg of DOPAC injected) and reproducible (coefficient of variation 0.4-1%) with good accuracy (94-98%).

Rapid and sensitive assay of dobutamine in plasma by high-performance liquid chromatography and electrochemical detection

A sensitive and specific high-performance liquid chromatographic method with electrochemical detection was developed for measuring dobutamine in human plasma samples. Following an external standard method, 0.1 ml of EDTA-glutathione plasma was diluted on ice with 0.2 ml of a 5% trichloracetic acid solution. The mixture was centrifuged, filtered, and 30 microliters were injected. Assessment was done by electrochemical detection. The assay was linear from 1 to 400 ng/ml plasma. For determination of dobutamine we also used a liquid-liquid extraction method routinely applied for plasma catecholamines. Liquid-liquid extraction requires application of 100-1000 microliters of plasma. The standard curve was linear from 0.1 to 600 ng/ml. Absolute recovery of dobutamine was 90 +/- 3% with the liquid-liquid extraction procedure and 91 +/- 3% with the protein precipitation method. For both methods dobutamine was separated on Nova-Pak C18 columns. The mobile phase used was 0.1 molar phosphate buffer-acetonitrile (80:20, v/v) with 1-octanesulfonic acid and triethylamine as ion-pair reagents. The pH was adjusted to 2.7.

Catecholamines and thrombocyte alpha 2-adrenoceptors in patients with acute myocardial infarction

In 28 patients with first myocardial infarction plasma catecholamines and thrombocyte alpha 2-adrenoceptors were studied. The first determination (by HPLC and radioligand binding, respectively) was performed immediately after hospital admission and 6 weeks later. In the acute phase of myocardial infarction plasma adrenaline and noradrenaline levels were high. No significant differences in thrombocyte alpha 2-adrenoceptors and plasma concentrations of adrenaline and noradrenaline were observed between diabetic and non-diabetic patients. In three non-surviving patients only the affinity of the alpha 2-adrenoceptor to the radioligand was decreased (P less than 0.05), the relatively high catecholamine levels failed to reach statistical significance. Six weeks after hospital admission, adrenaline plasma levels were significantly decreased in diabetic and non-diabetic patients, while noradrenaline was only lowered in non-diabetic patients (P less than 0.05). Only in this group did the receptor number (BMAX) show a significant elevation 6 weeks after hospital admission. We conclude that, in acute myocardial infarction, alpha 2-adrenoceptors mainly interact with noradrenaline. Accordingly, no adrenoceptor alteration occurred in diabetic patients, who showed only a decrease in adrenaline but not in noradrenaline plasma concentrations 6 weeks following myocardial infarction. The different patterns in diabetic and non-diabetic patients suggest an alteration of catecholamine metabolism in diabetes mellitus.

Time course of alpha 2-adrenoceptor desensitization induced by adrenaline infusion in man

After a rapid increase in infusion rate of adrenaline to elevate the initial heart rate by more than 15%, a continuous infusion was sustained in order to maintain elevated adrenaline plasma levels. At the end of the first phase of the experiment, the thrombocyte alpha 2-adrenoceptor number (determined by radioligand binding) was significantly lowered. After the second part of the experiment, a further significant decrease in the density of binding sites was observed, while elevated adrenaline plasma levels were kept constant. The decrease in the number of binding sites was accompanied by a slight increase in affinity of the radioligand. Serum potassium concentration significantly decreased during the experiment, while other serum electrolytes showed no significant alterations.

Separation by different methods of soluble proteins isolated from sympathetic splenic nerves

The soluble proteins of sympathetic splenic nerves were separated by high-performance liquid chromatography (HPLC), sodium dodecyl sulphate (SDS)-HPLC on TSK-GEL-SW columns and SDS-polyacrylamide gel electrophoresis (PAGE). With HPLC the main fractions had apparent molecular weights Mr 150,000, 75,000-85,000, 27,000 and less 5000, with SDS-HPLC the Mr values were 75,000, 13,500 and less 5000 and with SDS-PAGE the Mr were 75,000, 55,000, 45,000 and less 12,500. Of the proteins eluted after electrofocusing, the bands of pH 4.0-5.2 showed a single peak of Mr 75,000 in all separation methods used; in the range pH 5.8-6.5, proteins with Mr 150,000 were found by HPLC, 75,000 by SDS-HPLC and 55,000 and 45,000 by SDS-PAGE. The Mr 150,000 fraction in the range pH 5.8-6.5 showed DOPA decarboxylase (E.C. 4.1.1.28) activity. The results provide new information about the soluble proteins of sympathetic nerve.